Pumps delivering relatively small amounts of fluid are known. Such pumps typically employ fluid elements, such as elastic tubes or diaphragms, to draw and deliver fluid at a predetermined rate. These pumps may be magnetically driven, employing bipolar or dipole magnets (magnets having two opposite poles widely spaced at opposing edges or ends) for compressing the diaphragms or tubes. Although such magnets provide relatively extensive magnetic fields, the corresponding magnetic forces are weak. These pumps typically incorporate specially manufactured components and require substantial power to operate. Moreover, they are particularly noisy in operation.
Also known are peristaltic pumps employing rotating disks with protrusions which pinch circumscribing rubber tubes to pump fluid at a rate proportional to the rotation frequency of the disks. Peristaltic pumps are popular in the medical field, especially for intravenous medication or dietary supplements. Although such pumps are relatively quiet, they are also costly and complex in structure. Furthermore, because the tubes are repeatedly exposed to the protrusions on the rotating disk, the tubes must be replaced frequently.
Specific examples of known pumps are discussed, for example, in U.S. Pat. No. 3,171,360, issued to Walton. Therein, a vibration pump is disclosed, having a resilient tubular conduit and a striker reciprocable at a high frequency against one side of the tubular conduit, a support opposite the area of impact of the striker having an engaging face inclined at an acute angle relative to the tubular conduit, and means for reciprocating the striker at high frequency and through a short stroke relative to the diameter of the tubular conduit.
Also, in U.S. Pat. No. 4,014,318, issued to Dockum, et al., a circulatory assist device and structure are disclosed, providing an electrically operated plunger momentarily occluding the blood vessel to effect pumping, wherein a plurality of assist devices may be mounted adjacent each other and are sequentially actuated to occlude adjacent segments of the associated blood vessel, thereby creating a pumping action.
Moreover, a non-sucking pulsatile outflow continuous inflow pump is disclosed in U.S. Pat. No. 3,518,003, issued to Anderson, consisting of a first distensible body forming a chamber which is flat in cross-section when the body is in repose, this first body serving as a ventricle chamber, means forming an inlet and an outlet to the chamber, the inlet interconnecting the ventricle with an atrium comprised of an additional distensible body, and valves and impellers associated with the ventricle and atrium chambers arranged for synchronous operation of the valves and impellers to produce a pulsatile discharge from the ventricle outlet and a continuous unrestricted inflow of liquid to the atrium.
As indicated, these pumps are substantially complex in structure and require special components which increase their cost and maintenance. In particular, where dipole or bi-polar magnets are utilized to supply the necessary magnetic force to drive such pumps, the pumps can become quite expensive.
Accordingly, there exists a demand for a simple and quiet magnetically-driven pump that is relatively inexpensive to manufacture and operate. It is desired that such a magnetically-driven pump use inexpensive, off-the-shelf components, but provide enough force to pump fluid to a substantial height. It is also desired that such a magnetically-driven pump be compact and light. It is further desired that such a magnetically-driven pump be energy-efficient, requiring low voltage and current for operation, and be appropriate for personal use with minimal operating noise.
In accordance with the present invention, a magnetically-driven pump transferring fluid through a conduit is provided, having an electromagnet assembly selectively excited by a power source, and a non-ferromagnetic lever structure extending from the electromagnet assembly to the conduit, the lever structure having a ferro-magnetic portion at one end movable by the electromagnet assembly between a release position where the ferro-magnetic portion is angularly offset relative to the electromagnet assembly and a compression position where the ferro-magnetic portion is in substantially parallel contact with the electromagnet assembly, the ferro-magnetic portion enabling a striker portion at another end of the lever structure to compress the conduit at a predetermined frequency. The lever structure couples movement of the ferro-magnetic portion at one end with movement of a striker at the other end such that the ferro-magnetic portion moves within a lesser arcuate range and the striker moves within a greater arcuate range. To reduce operating noise, the lever may be pivotally mounted on a translating shaft, enabling a part of the ferro-magnetic portion to remain in contact with the electromagnet assembly while in and between the release and compression positions.
These, as well as other features of the invention, will become apparent from the detailed description which follows, considered together with the appended drawings.